Valuable metals and minerals are frequently contained in subterranean deposits referred to in the art as “ore bodies”. Such ore bodies are typically located at varying depths in hard or high strength barren rock. Before mining can commence, a number of underground excavations must be developed at a plurality of levels to facilitate access to the ore body at each level.
Several methods have been developed to mine such ore bodies to recover the valuable metals or minerals, some examples of which are described, in U.S. Pat. No. 6,857,706. During mining operations, each cut or “panel” of ore is removed sequentially by drilling a plurality of vertically extending boreholes, loading explosive charges into each borehole and blasting. The blasted ore or rock material is gathered or “mucked” to a loading or draw point. Thereafter, a cavity referred to in the art as a “stope” is created by removal of the broken ore is backfilled with waste material such as mine tailings, concrete, cement rock fill, or paste fill.
Once rock is fragmented, the release of pressure causes it to expand therefore occupying a larger volume than before. Using the processes of the prior art, a space or void for receiving the fragmented rock is created by mining an elongated substantially vertical or inclined shaft extending between a lower level and an upper level of the mine, referred to in the art as a “rise”. Developing a rise for every production panel of the stope being mined can be both time consuming and expensive.
There remains a need for more efficient or economical methods for underground mining.